The invention relates to a dismantling-type antenna with a capacitive load, of whip type, known as a whip antenna; such an antenna, whether it can be dismantled or not, features a wide band of operating frequencies.
It is known to further widen this band by combining the antenna with a tuning unit, known as an Antenna Tuning Unit; this tuning unit has the role of providing perfect impedance matching throughout the working band.
It is known to produce a whip-type antenna with capacitive loads in different ways, which will be illustrated with the aid of FIGS. 2a, 2b, 2c attached and of the description relating to them.
However, these embodiments do not give entire satisfaction since either the antenna is relatively fragile in the region of the capacitive load, or a mechanical reinforcement has to be provided at this spot, which renders manufacture expensive.
The U.S. Pat. No. 4,958,164 describes a dismantling-type antenna which operates in the wideband domain. It consists of several linear radiating elements arranged in series, one of which includes a capacitor.
In the U.S. Pat. No. 5,836,072, there is described a method for assembling an antenna, and more particularly the manner of coating the elements of an antenna with a thermoplastic material.
The object of the present invention is to avoid or, at least, to reduce these drawbacks.
This is achieved principally by virtue of a specially designed capacitive load, arranged so as not to weaken the antenna.
According to the invention, a dismantling-type antenna is therefore proposed, with a capacitive load, of whip type, including several radiating segments separate from one another and arranged end to end one after the other, each segment including a conducting stretch which extends over the whole length of the segment, characterized in that at least one of the segments includes a capacitive load, inserted integrally into its conducting stretch, and a hollow insulating tube which serves as a support for the conducting stretch and within which the capacitive load is housed, in that the capacitive load includes a first armature consisting of a metal enclosure, a second armature consisting of a length of a conducting wire covered with an insulating sheath, this length of wire being located in the enclosure and at least one of its ends being situated at the limit of the enclosure and being extended out of the enclosure so as to constitute an access to the second armature.
According to the invention, a method is also proposed for manufacturing a radiating segment of a dismantling-type antenna, with a capacitive load, of whip type, characterized in that it includes at least the following stages:
arranging a ferrule around a support, such as a mandrel, including a first and a second end,
pushing in the capacitive load including a metal block and a metal wire, at a first end of the said support,
arranging a conducting element around the said mandrel, such as a braid secured to the two ends of the support,
surrounding the assembly thus formed with a protective means, such as a protective envelope made of glass-fibre reinforced plastic, the said protective means extending between the outlet wire from the load and the second end of the support,
subjecting the assembly to a hardening stage,
withdrawing the support element.